"And unto the angel of the church in Thyatira write; These things saith the Son of God, who hath his eyes like unto a flame of fire, and his feet are like fine brass; I know thy works, and charity, and service, and faith, and thy patience, and thy works; and the last to be more than the first. Notwithstanding I have a few things against thee, because thou sufferest that woman Jezebel, which calleth herself a prophetess, to teach and to seduce my servants to commit fornication, and to eat things sacrificed unto idols. And I gave her space to repent of her fornication; and she repented not. Behold, I will cast her into a bed, and them that commit adultery with her into great tribulation, except they repent of their deeds. And I will kill her children with death; and all the churches shall know that I am he which searcheth the reins and hearts: and I will give unto every one of you according to your works. But unto you I say, and unto the rest in Thyatira, as many as have not this doctrine, and which have not known the depths of Satan, as they speak; I will put upon you none other burden. But that which ye have already hold fast till I come. And he that overcometh, and keepeth my works unto the end, to him will I give power over the nations: And he shall rule them with a rod of iron; as the vessels of a potter shall they be broken to shivers: even as I received of my Father. And I will give him the morning star. He that hath an ear, let him hear what the Spirit saith unto the churches."--Revelation 2:18-29
"Thyatira...main industry was dyeing cloth a beautiful red or purple...There were many trade guilds in the city, and it was almost impossible to do well in business without belonging to one of these guilds. That became a problem for believers because paganism and immorality were rife in guild life.
"There was also a temple for fortune-tellers in Thyatira, with a powerful female oracle presiding over it at this time."
(There's A New World Coming, Hal Lindsey)
"Thyatira was in the 1st century AD a station on the Imperial Post Road (overland route)...In its connexion with Pergamum this road had always a great importance...The city was founded...as a defence against Lysimachus...was a useful garrison to hold the road...The relation between Pergamum and Thyatira was thus of the closest. The city, though weak in posiiton, was a garrison city, and had to be carefully fortified, and everything was done to foster the military spirit. The character of the city's religion is illustrateed by the hero Tyrimnos, who is figured on its coins. He is on horseback and has a battle-axe on his shoulder. This hero is closely related to the protecting god of the city, whose temple was in front of the city. He was considered the divine ancestor of the city and its leading families, and was identified with the sun-god...In conformity with this, he was represented as wearing a cloak fastened by a brooch, carrying a battle-axe, and with a laurel branch in his right hand, symbolizing his purifying power.
"Its situation demands that it be captured and re-fortified by every ruling power. In Roman times it had been a great trading city, dating its greatest period of prosperity from about the time when the Seven Letters were written. There is evidence of more trade-guilds there than in any other Asian city: wool-workers, linen-workers, makers of outer garments, dyers, leather-workers, tanners, bronze-smiths, etc."
(Hastings' Dictionary of the Bible)
"Another superstition, of an extremely curious nature, which existed at Thyatira, seems to have been brought thither by some of the corrupted Jews of the dispersed tribes. A fane [temple] stood outside the walls, dedicated to Sambatha--the name of the sibyl who is sometimes called Chaldean, soemetimes Jewish, sometimes Persian--in the midst of an inclosure designated 'the Chaldean's Court.'
"If the sibyl Sambatha was really a Jewess, lending her aid...and not discountenanced by the authorities of the Judeo-Christian chruch at Thyatira, both the censure and its qualification become easy of explanation."
(Dr. William Smith's Dictionary of the Bible, 1872)
"The prophetic utterances of women called sibyls in ancient Greece and Rome, believed to have been inspired by the god Apollo; collections of these utterances played an important part in the religious history of ancient Rome...They are now believed to have been composed by Jews, and later by Christians, both groups imitating earlier pagan oracles in their attempts to win converts..."
(Universal Standard Encyclopedia)
See the online book The Letters to the Seven Churches of Asia by W. M. Ramsay.